diff --git a/prody/proteins/ciffile.py b/prody/proteins/ciffile.py
index a9df3ecdb..2c5955202 100644
--- a/prody/proteins/ciffile.py
+++ b/prody/proteins/ciffile.py
@@ -194,7 +194,7 @@ def parseMMCIFStream(stream, **kwargs):
     if segment is not None:
         if not isinstance(segment, str):
             raise TypeError('segment must be a string')
-        elif len(chain) == 0:
+        elif len(segment) == 0:
             raise ValueError('segment must not be an empty string')
         title_suffix = '_' + segment + title_suffix
 
diff --git a/prody/tests/proteins/test_ciffile.py b/prody/tests/proteins/test_ciffile.py
index b302f3c7e..f81b7c907 100644
--- a/prody/tests/proteins/test_ciffile.py
+++ b/prody/tests/proteins/test_ciffile.py
@@ -159,7 +159,7 @@ def testUniteChainsAndBiomolArguments(self):
                         'parseMMCIF failed to parse correct numbers of chains '
                         'with biomol True and unite_chain False')
         
-        bm_header = parseMMCIF(path, biomol=True)[0]
+        bm_header = parseMMCIF(path, biomol=True, header=True)[0]
         self.assertEqual(bm_header[0].numAtoms(), 
                         self.biomols['bm0_atoms'],
                         'parseMMCIF failed to parse correct number of atoms '